ClickHouse 26.8: pin synchronous inserts, 26.8-safe fixtures, CI on 26.8

[ar2rsawseen]

Why

countly-platform now runs ClickHouse 26.8 (floor 26.8.6). Two things in that move reach the migrator:

• 26.8 reads a bare JSON number for a DateTime64 column as seconds, so a millisecond epoch lands on 9999-12-31 unless input_format_read_datetime_number_as_raw_value=1 (platform runbook: docs/runbooks/clickhouse-26.8-upgrade.md).
• Countly's ClickHouse default profile sets async_insert=1 (deploy/compose/clickhouse/users.d/async-insert.xml, Helm countly-clickhouse profile). The migrator never set it, so its staging inserts silently became async inserts.

What changes

• StagingManager sets async_insert: 0 on its client. Verify-then-attach counts rows right after an insert and needs an ack to mean the rows are written. Under the profile that held only while wait_for_async_insert stays on, which is an env knob there (CLICKHOUSE_WAIT_FOR_ASYNC_INSERT).
• Timestamps need no change: ts/cd/lu are written as quoted yyyy-MM-dd HH:mm:ss.SSS strings, which parse the same on every version with or without the setting. A comment there now says why they must stay strings.
• Test fixtures that inserted bare ms numbers into ts in VALUES now use fromUnixTimestamp64Milli(...). On a 26.8 server without the setting, a bare number stores 9999-12-31.
• The ledger e2e test creates the platform's real drill_events DDL (codecs, cd_minmax, object serialization settings) and asserts:
  • exact stored ts/cd/lu and partitions;
  • zero rows in year 9999;
  • every insert in the run had async_insert=0 (from system.query_log).
• CI moves from clickhouse-server:26.4 to stock 26.8. The stock image has no Countly profile, so the raw-value setting is off: the strictest case, as on an external ClickHouse. The opt-in outage test defaults to 26.8 too.

Already compatible, no change needed:

• Overflowing integers in event data. sanitizeJsonValue already stringifies them with the same bounds as the platform's eventTransformer.ts.
• Unquoted 64-bit ints in JSON output on 26.x. Every ClickHouse read goes through Number(), and the cd checksum is reduced mod 2^32, so nothing exceeds 2^53. Content sampling compares timestamps as text and JSON columns by key set.

How it was tested

Run against ClickHouse 26.8.17 with Countly's production profile (async_insert=1, raw-value=1) and MongoDB 8.3:

• Before the change, the suite passed (100 integration tests), but query_log showed every staging insert as an async insert.
• After the change, vitest run tests/differential tests/integration passes: 174 passed, 1 skipped (opt-in outage).
• With the async_insert: 0 line removed, the new e2e assertion fails (['1'] vs ['0']), so it guards the pin.
• With the raw-value setting forced off (an external 26.8 without the profile), a transformed row stored the right ts/lu/cd (2025-09-04). A bare-number control row stored 9999-12-31.

🤖 Generated with Claude Code

[Copilot]

Copilot was unable to review this pull request because the user who requested the review has reached their quota limit.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-14T13:03:18.302109Z	50324d8	PR opened

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.